Field of the Invention and Related Art Statement
The present invention relates to an apparatus for mounting automatically various kinds of chip devices on a printed circuit board.
Such an apparatus is generally called "Chip Mounter" and has been used for mounting active chip devices such as IC, transistor and diode chips as well as passive chip devices such as resistor capacitor and coil chips.
Various kinds of chip mounters have been developed. Usually a number of chip devices of the same kind are arranged in a tape which is wound as a coil. In a known chip mounter, a plurality of tape coils are set on a plurality of tape units arranged side by side and these tape units are moved with respect to a mounting head. After a tape unit on which a tape coil having desired chip devices has been indexed into the mounting head, one chip device is supplied from the tape unit to the mounting head. Then the mounting head is indexed at a given position on a printed circuit board placed on an XY table and the chip device is mounted on the printed circuit board.
In such an apparatus the chip device to be mounted is held at a lower end of the mounting head with the aid of a suction force, and therefore the number of different kinds of chip devices which can be mounted by the single mounting head can not be made large. Therefore, there has been also proposed a chip mounter in which a plurality of mounting units, each composed of a tape unit, mounting head and XY table, are arranged in series with each other and a printed circuit board is transported through successive mounting units, while desired chip devices are mounted on the circuit board in respective mounting units.
There is further proposed a chip mounter including a plurality of mounting heads each holding chip devices having different sizes and shapes and a desired mounting head is selectively used in accordance with a chip device to be mounted.
In the known chip mounter in which a number of tape units are moved with respect to the single mounting head, it is required to provide a large scale driving mechanism for moving the heavy and long tape unit assembly in a reciprocal manner. It is apparent that such a mechanism could not move the tape unit assembly at a high speed, and thus the mounting rate is limited. Particularly, when it is required to mount many different kinds of chip devices, the weight and length of the tape unit assembly become large and the mounting rate would be further decreased. Moreover, the range over which the tape unit assembly is moved is quite long, so that the space factor of the chip mounter is very small.
In the known chip mounter in which a plurality of mounting units are arranged side by side and a printed circuit board is transported through these mounting units, the whole apparatus is liable to be very large and expensive. Further, there is additionally required mechanisms for moving th printed circuit board between successive mounting units. Therefore, the mounting rate is also limited.
In the known chip mounter in which a plurality of mounting heads are selectively used, the apparatus may be made rather small, but the construction of the mounting head assembly becomes quite complicated and the mounting rate low, because the changing of mounting heads requires a relatively long time.